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#11
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How are the Japanese doing that?
On Jun 21, 6:04*pm, Pat Flannery wrote:
It was made into a reliable form of propulsion from what was learned from DS-1 though, and our Dawn asteroid mission is using it right now:http://dawn.jpl.nasa.gov/ It has improved although it still tends to have some problems (eg:all the failures on this particular flight). It seems to be a good engine once its firing and is left alone, but seems to have problems in other environments. The question though is whether its better than other forms of Electrical propulsion. Probably mute point that given the paucity of such flights. What few people remember (and NASA didn't exactly advertise) is that US tests of ion space propulsion went _decades_ back before DS-1; behold SERT 2 and its _nuclear-powered_ ion drive from 1970:http://www.astronautix.com/craft/sert.htm Argh the good ole days when actual space research was undertaken. Note though, that this is mercury Ion thrusters as opposed to the newer ones. |
#12
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How are the Japanese doing that?
On 6/21/2010 2:53 PM, Brian Thorn wrote:
So did Stardust's. It was Genesis that went splat. The thing is, if someone had walked into JPL and said: "Here's what we want the new spacecraft to do: 1. Cruise out to a asteroid under ion power. 2. Autonomously rendezvous with said asteroid without Earth command. 3. Land on said asteroid. 4. Deploy sample collecting robot. 5. Return samples to main spacecraft with the robot collector. 6. Lift off from surface of asteroid and re-engage ion engines. 7. Return to Earth and drop sample to Earth's surface in recoverable capsule." ....their response would be "And we have how many years and billions of dollars to do this?". Between that and the JAXA solar sail spacecraft (we were going to launch one of those to Halley's comet the last time it went by in 1986, but never got around to it) take a wild guess who is seizing the high ground in unmanned space exploration, and doing it on a tight budget to boot? Then there's the HTV - the Dragon won't dock at the ISS on its first fully functional test flight. Guess who's could? We are worrying about China and India - forget them...this is the crew that's seizing the high frontier big time. Pat |
#13
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How are the Japanese doing that?
On Jun 23, 3:37*am, Pat Flannery wrote:
On 6/21/2010 2:53 PM, Brian Thorn wrote: So did Stardust's. It was Genesis that went splat. The thing is, if someone had walked into JPL and said: "Here's what we want the new spacecraft to do: 1. Cruise out to a asteroid under ion power. 2. Autonomously rendezvous with said asteroid without Earth command. 3. Land on said asteroid. 4. Deploy sample collecting robot. 5. Return samples to main spacecraft with the robot collector. 6. Lift off from surface of asteroid and re-engage ion engines. 7. Return to Earth and drop sample to Earth's surface in recoverable capsule." ...their response would be "And we have how many years and billions of dollars to do this?". Between that and the JAXA solar sail spacecraft (we were going to launch one of those to Halley's comet the last time it went by in 1986, but never got around to it) take a wild guess who is seizing the high ground in unmanned space exploration, and doing it on a tight budget to boot? Then there's the HTV - the Dragon won't dock at the ISS on its first fully functional test flight. Guess who's could? We are worrying about China and India - forget them...this is the crew that's seizing the high frontier big time. As Brian pointed out, NASA already did sample returns, and without spending billions or many years. Even in the partial failure of the Genesis recovery, viable samples were still recovered for study, It also remains to be seen what, if anything, Hayabusa brought back as the spacecraft suffered through mulitple failures on it's attempts to land and obtain a sample. Also among the failures was the MINERVA miniprobe that due to another error was improperly released and failed to reach the surface of asteroid Itokawa. Overall the Japanse can be proud of pulling the mission through so many mulitple failures, and they will gain a huge amount of engineering data as well as the science that was done in proximity to Itokawa, but let's not go overboard here and make this out to be something that it is not, either. -Mike |
#14
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How are the Japanese doing that?
On Wed, 23 Jun 2010 02:37:43 -0800, Pat Flannery
wrote: So did Stardust's. It was Genesis that went splat. The thing is, if someone had walked into JPL and said: "Here's what we want the new spacecraft to do: 1. Cruise out to a asteroid under ion power. 2. Autonomously rendezvous with said asteroid without Earth command. 3. Land on said asteroid. No, they just nudged right up next to it. NEAR Shoemaker did that ten years ago. 4. Deploy sample collecting robot. 5. Return samples to main spacecraft with the robot collector. I think the sample collector and the robot were two different things. The robot didn't work. The collector barely did (maybe getting some dust, it failed to get a solid sample.) 6. Lift off from surface of asteroid and re-engage ion engines. 7. Return to Earth and drop sample to Earth's surface in recoverable capsule." ...their response would be "And we have how many years and billions of dollars to do this?". I'm still not convinced. I think it would be either a Discovery-class (it is essentially a combination of three NASA Discovery-class missions... NEAR and Stardust using Dawn's engine) or a more expensive New Horizons mission, it wouldn't be a flagship mission. Between that and the JAXA solar sail spacecraft (we were going to launch one of those to Halley's comet the last time it went by in 1986, but never got around to it) NASA tried to launch a solar sail a couple of years ago. SpaceX dumped it in the Pacific Ocean. The Planetary Society tried as well, the Russian rocket launching it was never seen again. take a wild guess who is seizing the high ground in unmanned space exploration, The U.S., by a very wide margin. and doing it on a tight budget to boot? Japan is following the U.S.'s lead with the FBC programs, Discovery and New Frontiers. Then there's the HTV - the Dragon won't dock at the ISS on its first fully functional test flight. Guess who's could? That's because of SpaceX's very low budget and HTV's very high cost. SpaceX can't afford to do everything on the first flight, JAXA couldn't afford not to. And neither actually docks. They're grabbed by the Station's arm and berthed. We are worrying about China and India - forget them...this is the crew that's seizing the high frontier big time. One mission that sputters its way to the finish line after seven years is "seizing the high frontier big time"? Since Hayabusa launched in 2003 the U.S. launched: MER-A Spirit MER-B Opportunity Messenger Deep Impact Mars Reconnaissance Orbiter New Horizons Mars Phoenix Dawn Lunar Reconnaissance Orbiter Japan has launched its lunar and Venus probes in the same period. Oh, yes, Japan is really surging ahead. :-/ Brian |
#15
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How are the Japanese doing that?
On Wed, 23 Jun 2010 13:12:13 -0700 (PDT), Mike DiCenso
wrote: Overall the Japanse can be proud of pulling the mission through so many mulitple failures, and they will gain a huge amount of engineering data as well as the science that was done in proximity to Itokawa, but let's not go overboard here and make this out to be something that it is not, either. Exactly. It was not my intention to belittle the achievements of Hayabusa. Brian |
#16
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How are the Japanese doing that?
On Jun 23, 4:03*pm, Brian Thorn wrote:
On Wed, 23 Jun 2010 02:37:43 -0800, Pat Flannery wrote: So did Stardust's. It was Genesis that went splat. The thing is, if someone had walked into JPL and said: "Here's what we want the new spacecraft to do: 1. Cruise out to a asteroid under ion power. 2. Autonomously rendezvous with said asteroid without Earth command. 3. Land on said asteroid. No, they just nudged right up next to it. NEAR Shoemaker did that ten years ago. 4. Deploy sample collecting robot. 5. Return samples to main spacecraft with the robot collector. I think the sample collector and the robot were two different things. The robot didn't work. The collector barely did (maybe getting some dust, it failed to get a solid sample.) 6. Lift off from surface of asteroid and re-engage ion engines. 7. Return to Earth and drop sample to Earth's surface in recoverable capsule." ...their response would be "And we have how many years and billions of dollars to do this?". I'm still not convinced. I think it would be either a Discovery-class (it is essentially a combination of three NASA Discovery-class missions... NEAR and Stardust using Dawn's engine) or a more expensive New Horizons mission, it wouldn't be a flagship mission. Between that and the JAXA solar sail spacecraft (we were going to launch one of those to Halley's comet the last time it went by in 1986, but never got around to it) NASA tried to launch a solar sail a couple of years ago. SpaceX dumped it in the Pacific Ocean. The Planetary Society tried as well, the Russian rocket launching it was never seen again. take a wild guess who is seizing the high ground in unmanned space exploration, The U.S., by a very wide margin. and doing it on a tight budget to boot? Japan is following the U.S.'s lead with the FBC programs, Discovery and New Frontiers. Then there's the HTV - the Dragon won't dock at the ISS on its first fully functional test flight. Guess who's could? That's because of SpaceX's very low budget and HTV's very high cost. SpaceX can't afford to do everything on the first flight, JAXA couldn't afford not to. And neither actually docks. They're grabbed by the Station's arm and berthed. We are worrying about China and India - forget them...this is the crew that's seizing the high frontier big time. One mission that sputters its way to the finish line after seven years is "seizing the high frontier big time"? Since Hayabusa launched in 2003 the U.S. launched: MER-A Spirit MER-B Opportunity Messenger Deep Impact Mars Reconnaissance Orbiter New Horizons Mars Phoenix Dawn Lunar Reconnaissance Orbiter Brian, you forgot to add the Lunar Crater Observation and Sensing Satellite (LCROSS). On a smaller scale, NASA also hitched instruments on other agencies' spacecraft during that time, such as the ASPERA-3 on ESA's Mars Express, and miniSAR as well as the Moon Mineralogy Mapper instruments on Chandrayaan-1. -Mike |
#17
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How are the Japanese doing that?
On Jun 23, 4:04*pm, Brian Thorn wrote:
On Wed, 23 Jun 2010 13:12:13 -0700 (PDT), Mike DiCenso wrote: Overall the Japanse can be proud of pulling the mission through so many mulitple failures, and they will gain a huge amount of engineering data as well as the science that was done in proximity to Itokawa, but let's not go overboard here and make this out to be something that it is not, either. Exactly. It was not my intention to belittle the achievements of Hayabusa. No, certainly you weren't. You were just tossing cold water on NASA bashing stroke-fest that was going on there. ;-) -Mike. |
#18
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How are the Japanese doing that?
On Jun 21, 3:56*pm, Brian Thorn wrote:
On Sun, 20 Jun 2010 18:17:10 -0700 (PDT), Brad Guth wrote: There's no possible comparison, as the Hayabusa was at least ten fold more complex. Nonsense. Hayabusa was a combination of NASA's NEAR Shoemaker, Stardust and Deep Space 1 missions. At most, this would seem to add up to three times more complex. But of course, it actually isn't because, for example, launch and return are no more complex for Hayabusa than they were for Stardust, DS1 had already proven ion propulsion was viable over long durations, and setting down on the asteroid was no more complex than it was for NEAR (in fact, probably less, since Hayabusa was actually designed to do that.) Your belittlement and discrediting of others is noted. So is your refusal to address any of the points I made or to simply admit that you have no idea what you're talking about. I stand by my assessment that your "no possible comparison" assertion is utter nonsense. Brian Other fellow Semites would naturally have to agree with that. ~ BG |
#19
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How are the Japanese doing that?
On Sat, 26 Jun 2010 12:12:17 -0800, Pat Flannery
wrote: However, the spacecraft did come in contact with the asteroid itself, not once - but twice - to try and recover a sample...and given the low gravity of the asteroid, that's as close as you could get to landing on it. Again... that's something NEAR did ten years ago. Brian |
#20
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How are the Japanese doing that?
On 6/23/2010 3:03 PM, Brian Thorn wrote:
1. Cruise out to a asteroid under ion power. 2. Autonomously rendezvous with said asteroid without Earth command. 3. Land on said asteroid. No, they just nudged right up next to it. NEAR Shoemaker did that ten years ago. 4. Deploy sample collecting robot. 5. Return samples to main spacecraft with the robot collector. I think the sample collector and the robot were two different things. The robot didn't work. The collector barely did (maybe getting some dust, it failed to get a solid sample.) My bad: I thought the robot was related to the sample collection system, but it was separate from it. However, the spacecraft did come in contact with the asteroid itself, not once - but twice - to try and recover a sample...and given the low gravity of the asteroid, that's as close as you could get to landing on it. Pat |
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